It has not been considered feasible in the past to transport refined hydrocarbon fluids in a pipeline used for the transportation of sour hydrocarbon fluids such as crude oil. The major difficulty is that refined hydrocarbon fluids such as gasoline and diesel fuel pick-up contaminants such as elemental sulfur. Between about 10 to 80 mg/L elemental sulfur is picked up by pipelined gasoline and between about 2 to 20 mg/L elemental sulfur is picked up by diesel. The copper strip corrosion by ASTM D-130 of these fuels is 4a/4b. Elemental sulfur has particularly corrosive effect on equipment such as brass valves, gauges, silver bearings cage in two-cycle engine and in-tank fuel pump copper commutators. Addition of copper corrosion inhibitor is used to meet ASTM D-130 copper strip ratings of 1a/1b but does not provide sufficient good corrosion protection in all types of equipment.
While numerous factors such as aromatics content, pipeline temperature, batch size, batch sequencing, line outage, pigging, etc. have been found to affect the elemental sulfur pick-up in the pipeline. No correlation of these variables with the actual level of elemental sulfur pick-up by the fuel has been found. Regardless, however, most of these factors are not controllable anyway.
As a result, few patents have appeared in the patent literature dealing with transportation of hydrocarbons in pipelines used for sour hydrocarbon fluids.
U.S. Pat. No. 4,071,882 described a method for minimizing sulfur contamination of refined hydrocarbon fluids transported in a pipeline for the transportation of sweet and sour hydrocarbon fluids by a) mixing with the sour hydrocarbon fluids from 0 to about 2000 ppm of a corrosion inhibiting additive; b) transporting the sour hydrocarbon through the pipeline; c) transporting a sweet hydrocarbon wash solution containing from about 10 to about 2000 ppm of a mixture of light amines and heavy amines, up to about 2000 ppm of a corrosion inhibiting additive, up to about 500 ppm of a surfactant and up to about 1500 ppm of an alkanol containing from 1 to about 6 carbon atoms; and d) transporting refined hydrocarbon fluids containing up to about 200 ppm of a corrosion inhibiting additive, an amine having a molecular weight from about 31 to about 500 or mixtures thereof.